The palladium-catalyzed vinylation of organic halides provides a very convenient method for forming carbon-carbon bonds at unsubstituted vinylic positions. The reaction, reported by Heck (Palladium Reagents in Organic Synthesis, Academic Press, Canada 1985) can be used to prepare fine organics, pharmaceuticals, and specialty monomers. For example, the reaction allows a one-step synthesis of substituted styrenes from aryl bromides and is an excellent method for preparation of a wide variety of styrene derivatives. Heitz et al., Makromol Chem., 189, 119 (1968).
Vinyl toluenes have been reported as the product of a homogeneous palladium-catalyzed coupling of ethylene with bromotoluenes. The reaction is performed in a two-phase solvent system composed of N,N-dimethyl formamide and water. R. A. DeVries et al., Organometallics, 13, 2405 (1994).
U.S. Pat. Nos. 5,136,069 and 5,243,068 to R. A. DeVries et al. describe preparation of vinylically-unsaturated compounds by reaction of a halogenated organic compound with a hydrolytically-stable, vinylically-unsaturated precursor compound in the presence of (a) a homogeneous zerovalent palladium catalyst complex, (b) an inorganic hydrogen halide acceptor and (c) a diluent which is either water or an aqueous solution containing up to 95% by volume of organic solvent.
Arylation of propylene, ethylene, styrene, and methyl acrylate with iodobenzene was found to be catalyzed by metallic palladium in methanol to give methylstyrene, styrene, t-stilbene, and methyl cinnamate, respectively. Their yields and selectivities increased significantly by the addition of excess potassium acetate as an acceptor of hydriodic acid formed. Mori et al., Bull. Chem. Soc., Japan, 46, 1505 (1973).
A variety of styrene derivatives and 3-vinylpyridine were prepared in moderate to good yields by the palladium-tri-o-tolylphosphine catalyzed reaction of ethylene with aryl bromides or 3-bromopyridine, respectively. (Plevyak et al., J. Org. Chem., 43, 2454 (1970).
Alper et al. in J. Chem Soc. Chem. Comm., 1983, 1270-1271, discloses that alkenes can react with carbon monoxide, water, hydrochloric acid and a mixture of palladium and copper to produce the hydrocarboxylated branched chain carboxylic acid. Oxygen is necessary to succeed in the reaction.
A process for preparing the branched chain carboxylic acid ibuprofen is described in Japanese Patent Application (Kokai) No. 59-10545 (Mitsubishi Petrochemical, published January, 1984), which teaches that ibuprofen can be prepared by reacting p-isobutylstyrene with carbon monoxide and water or an alcohol in the presence of a palladium(II) catalyst and a peroxide, e.g., cumyl hydroperoxide.
A process for preparing aryl substituted aliphatic carboxylic acids or their alkyl esters is disclosed in U. S. Pat. No. 5,315,026. A 1-aryl substituted olefin is reacted with carbon monoxide in the presence of water or an alcohol at a temperature between about 25.degree. C. and about 200.degree. C. A mixture useful as a catalyst is a palladium compound and a copper compound with at least one acid-stable ligand. Ligands which may be used include monodentate or multidentate electron-donating substances such as those containing elements P, N, O and the like, and those containing multiple bonds such as olefinic compounds. Examples of such acid-stable ligands are trihydrocarbylphosphines, including trialkyl- and triarylphosphines, such as tri-n-butyl-, tricyclohexyl-, and triphenylphosphine; lower alkyl and aryl nitriles, such as benzonitrile and n-propionitrile; ligands containing pi-electrons, such as an allyl compound or 1,5-cyclooctadiene; piperidine, piperazine, trichlorostannate(II), and acetylacetonate; and the like.
U.S. Pat. No. 5,536,870 describes the preparation of substituted olefins by the palladium-catalyzed coupling of vinyl or substituted vinyl compounds with organic halides, and also the formation of carboxylic acids and esters from such substituted olefins. The substituted olefinic compounds are formed by reacting an organic halide with a vinyl or substituted vinyl compound in the presence of a catalytically effective amount of palladium or a salt of palladium having a valence of zero, 1 or 2, and a tertiary phosphine ligand such as neomenthyldiphenylphosphine. This reaction is carried out in the presence or absence of a solvent such as acetonitrile, tetrahydrofuran, dioxane, or dimethylformamide. An important utility of the substituted olefins formed in this manner is the subsequent conversion of such substituted olefins to carboxylic acids or derivatives thereof such as salts or esters (e.g., profen compounds) by carbonylation with carbon monoxide using catalytic systems and reaction conditions described in U.S. Pat. No. 5,536,870.